Prevalence of diabetic retinopathy among diabetic patients in a tertiary hospital
Ma. Florentina Fajardo-Gomez, MD, Harvey S. Uy, MD
DIABETIC retinopathy (DR) is a leading cause of
blindness worldwide, accounting for 2% of legally blind
and 10% of those with severe visual handicap, according
to the World Health Organization. In the United States,
it affects 50% of those with diabetes mellitus. Worldwide,
the prevalence rates range from 9% to 71%, and these
are expected to increase over the next 20 years.
on its prevalence among Filipino diabetic patients are,
This study determined the prevalence of DR among
Filipino patients with DM, its severity, and the risk factors
associated with it.
Two hundred and forty-one patients seen at the
outpatient Diabetes Clinic of the University of the
Philippines-Philippine General Hospital (UP-PGH), a
government-operated tertiary-care center in Metro
Manila, were recruited from March to August 1999. They
were interviewed using a standard questionnaire and their
medical charts reviewed to obtain the following data: age;
gender; family history of systemic diseases; medication and
smoking history; duration of DM; and levels of fasting
blood glucose (FBS), glycosylated hemoglobin, serum
creatinine, and serum cholesterol. Ophthalmic evaluation
included determination of the best-corrected visual acuity
(BCVA ), slitlamp evaluation, and a dilated-fundus
examination conducted by a single retina specialist
(MFFG) using noncontact biomicroscopy and indirect
ophthalmoscopy. The presence and severity of DR by
clinical examination was recorded. Stereo fundus
photography (SP) and fluorescein angiography (FA) were
performed on 147 patients and a separate assessment of
the presence and severity of DR by these methods was
made by a masked retina specialist (HSU). The severity
of DR was classified according to the PGH Retina Service
Diabetic Retinopathy Grading System (Table 1).
Informed consent was obtained from all patients. The
study protocol was reviewed and approved by the Ethics
Review Board of UP-PGH.
Chi-square and logistic regression were performed
using SAS and Epi-Info. The kappa coefficient was
computed to compare results of clinical examination, SP
and FA with patient variables. A p value of 0.05 or less was
Table 2 gives the demographic profile of the study population. The mean age of the patients was 55 years. 24.1%
had a family history of DM and 27% were smokers. 30.7%
of patients had DM of less than 5 years, 26.6% between 5
and 10 years, and 42.7% more than 10 years. At
enrollment, 75.9% had elevated FBS, 19.6% had elevated
serum creatinine, and 59.3% had elevated serum
cholesterol. Sixty (39.4%) of 153 females and 21 (24%)
of 88 males had DR.
61.8% of patients manifested DR on dilated-fundus
examination, 35.2% had no DR, and 2.9% had indeterminate findings due to associated ocular conditions such
as dense cataract or corneal scar that precluded adequate
fundus evaluation. The distribution according to severity
of DR is listed in Table 3.
Of the 147 patients who underwent SP and FA, 83.6%
had DR, 15.0% had no DR, and 1.4% had indeterminate
findings (Table 3). Approximately 20% had angiographic
evidence of proliferative disease.
More patients were diagnosed with diabetic retinopathy
by SP and FA than by clinical examination alone. A high
degree of agreement between clinical examination and SP
and FA was observed with a kappa value of 0.91 (p = 0.001).
Logistic-regression analysis of age, sex, medication,
family history, smoking history, fasting blood glucose,
glycosylated hemoglobin, and cholesterol levels did not
show significant association with DR. Duration of DM
(p = 0.02) and serum-creatinine levels (p = 0.04) were significantly related to the presence of DR. Elevated serum
creatinine was observed in 89 (60%) patients with DR.
Among 149 patients with clinical DR, 51 (34.2%) had DM
for less than 5 years, 32 (21.5%) for 5 to 10 years, and 66
(44.3%) for more than 10 years.
Diabetic retinopathy accounted for 85% of cases seen
at the UP-PGH Retina Clinic and 80% of retinal surgeries
(1998 Annual Report of the Department of Ophthalmology, UP-PGH). Majority had advanced disease at initial
The prevalence of DR in this series was higher
compared with those of other clinic-based studies.
Underprivileged patients, which comprise the majority of
patients seen at UP-PGH, have multiple barriers to
receiving medical care and obtaining medication
compared to private patients who have better access to
health care and were more likely to seek consultation
earlier. In this study, approximately 1 in 5 patients had
proliferative disease at the time of enrollment and were
at risk for visual loss. Many of them were unaware of having
DM. A dilated retinal evaluation is, therefore, recommended for all newly diagnosed DM patients. Measures
promoting early and regular screening for DR are also
needed to reduce the risk of blindness.
Concordance of clinical retinal evaluation and angiographic evidence of DR was high in this study, supporting
the usefulness of dilated retinal examination in screening
for retinopathy. However, the angiographic rate of DR was
higher (83.6%) compared to the clinical evaluation
(61.8%), suggesting a higher sensitivity of FA in detecting
retinopathy and the need to perform this procedure
As in other studies, the duration of DM and serumcreatinine level were significantly correlated with the
presence of DR. These risk factors can be used to
determine the frequency and interval of follow-up retinal
In summary, high prevalence of diabetic retinopathy
was seen among patients in a public tertiary-care center.
Elevated serum-creatinine level and longer duration of
DM were significantly associated with the presence of
retinopathy. Dilated retinal examination should be
recommended for all newly diagnosed DM patients, plus
regular follow-up to detect worsening of the retinopathy.
Periodic fluorescein angiography may be performed as
needed to better ascertain the status of the disease.
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